paleolimbot commented on code in PR #318:
URL: https://github.com/apache/arrow-nanoarrow/pull/318#discussion_r1395744762
##########
python/src/nanoarrow/lib.py:
##########
@@ -22,9 +22,10 @@ def schema(obj):
if isinstance(obj, Schema):
return obj
- # Not particularly safe because _export_to_c() could be exporting an
- # array, schema, or array_stream. The ideal
- # solution here would be something like __arrow_c_schema__()
+ if hasattr(obj, "__arrow_c_schema__"):
+ return Schema._import_from_c_capsule(obj.__arrow_c_schema__())
+
+ # for pyarrow < 14.0
Review Comment:
At some point we should maybe remove this logic (or do stricter
check...maybe using `type().__name__` or something). A name-based check would
support older pyarrow, anyway...I think it would be reasonable for any other
package that were using `_export_to_c()` to update and use the new dunder
method to be compatible here.
##########
python/src/nanoarrow/_lib.pyx:
##########
@@ -428,6 +477,33 @@ cdef class Array:
self._ptr = <ArrowArray*>addr
self._schema = schema
+ @staticmethod
+ def _import_from_c_capsule(schema_capsule, array_capsule):
+ """
+ Import from a ArrowSchema and ArrowArray PyCapsule tuple.
+
+ Parameters
+ ----------
+ schema : PyCapsule
+ A valid PyCapsule with name 'arrow_array' containing an
+ ArrowArray pointer.
Review Comment:
This seems like it should be updated?
##########
python/tests/test_capsules.py:
##########
@@ -0,0 +1,81 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements. See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership. The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License. You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied. See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+import pyarrow as pa
+
+import nanoarrow as na
+
+
+class SchemaWrapper:
+ def __init__(self, schema):
+ self.schema = schema
+
+ def __arrow_c_schema__(self):
+ return self.schema.__arrow_c_schema__()
+
+
+class ArrayWrapper:
Review Comment:
`Array(Stream)Wrapper` should also implement `__arrow_c_schema__`, right?
Even if not used here, it might be good for future readers who end up here to
see the example.
##########
python/src/nanoarrow/_lib.pyx:
##########
@@ -200,6 +227,28 @@ cdef class Schema:
self._base = base,
self._ptr = <ArrowSchema*>addr
+ @staticmethod
+ def _import_from_c_capsule(schema_capsule):
+ """
+ Import from a ArrowSchema PyCapsule
+
+ Parameters
+ ----------
+ schema_capsule : PyCapsule
+ A valid PyCapsule with name 'arrow_schema' containing an
+ ArrowSchema pointer.
+ """
+ cdef:
+ ArrowSchema* c_schema
+ Schema out
+
+ c_schema = <ArrowSchema*> PyCapsule_GetPointer(schema_capsule,
'arrow_schema')
+
+ out = Schema.allocate()
Review Comment:
I wonder if what you want here is more like:
```
cdef Array array = Schema(schema_capsule,
<uintptr_t>PyCapsule_GetPointer(schema_capsule, 'arrow_schema'))
```
(i.e., no need to "move" here...`base` can be a capsule, which does
basically the same thing as the `SchemaHolder`)
##########
python/tests/test_capsules.py:
##########
@@ -0,0 +1,81 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements. See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership. The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License. You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied. See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+import pyarrow as pa
+
+import nanoarrow as na
+
+
+class SchemaWrapper:
+ def __init__(self, schema):
+ self.schema = schema
+
+ def __arrow_c_schema__(self):
+ return self.schema.__arrow_c_schema__()
+
+
+class ArrayWrapper:
+ def __init__(self, array):
+ self.array = array
+
+ def __arrow_c_array__(self):
+ return self.array.__arrow_c_array__()
+
+
+class StreamWrapper:
+ def __init__(self, stream):
+ self.stream = stream
+
+ def __arrow_c_stream__(self):
Review Comment:
```suggestion
def __arrow_c_stream__(self, schema=None):
```
(right?)
##########
python/tests/test_capsules.py:
##########
@@ -0,0 +1,81 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements. See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership. The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License. You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied. See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+import pyarrow as pa
+
+import nanoarrow as na
+
+
+class SchemaWrapper:
+ def __init__(self, schema):
+ self.schema = schema
+
+ def __arrow_c_schema__(self):
+ return self.schema.__arrow_c_schema__()
+
+
+class ArrayWrapper:
+ def __init__(self, array):
+ self.array = array
+
+ def __arrow_c_array__(self):
Review Comment:
```suggestion
def __arrow_c_array__(self, schema=None):
```
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